Progress in imaging detectors has opened up a new optical design space. Recent developments include combining functions (daytime/nighttime/all weather imaging) that were previously only available with separate imaging detectors. For example, a single imaging detector is now able to image from 0.9 um to 5 um or 3 um to 12 um. Previously these wavelength bands were broken up into two separate smaller wavebands (short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) or MWIR and long-wavelength infrared (LWIR)) which required the use of two separate imaging detectors. In these smaller wavelength ranges, refractive optical systems for each separate waveband are typically preferred. However, as the imaging detector's bandwidth increases and therefore the optical system's bandwidth increases there are limited refractive optical materials available that can transmit over this increased spectral range. Furthermore, the materials that do exist make it difficult to provide color correction. For example, crowns switch to flints and flints switch to crowns when moving from the SWIR to the MWIR. This makes it challenging to design a compact lightweight refractive optical system for the entire waveband that can be used with the new imaging detectors. Plus, additional features such as multiple imaging field of views, handheld operation, and 100% cold shielding make it even more difficult to design a refractive optical system that meets all specifications over the increased spectral bandwidth requirements. Thus, there is a need for an optical system that addresses the shortcomings associated with the traditional refractive optical system. This need and other needs are satisfied by the optical system and method of the present invention.